Abstract
The Rad52 protein has critical functions in distinct pathways of the homology-directed DNA repair, one of which is to promote the annealing of complementary strands of DNA. Both yeast and human Rad52 proteins organize into ring-shaped oligomers with the predominant form being a heptamer. Despite the wealth of information obtained in previous investigations, how Rad52 mediates homology search and annealing remains unclear. Here, we developed single-molecule fluorescence resonance energy transfer approaches to probe hRad52-mediated DNA annealing events in real time. We found that annealing proceeds in successive steps involving rearrangements of the ssDNA-hRad52 complex. Moreover, after initial pairing, further search for extended homology occurs without dissociation. This search process is driven by an interaction between 2 overlapping nucleoprotein complexes. In light of these observations we propose a model for hRad52-mediated DNA annealing where ssDNA release and dsDNA zippering are coordinated through successive rearrangement of overlapping nucleoprotein complexes.
Original language | English (US) |
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Pages (from-to) | 20274-20279 |
Number of pages | 6 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 105 |
Issue number | 51 |
DOIs | |
State | Published - Dec 23 2008 |
Externally published | Yes |
Keywords
- DNA recombination
- DNA repair
- FRET
- Fluorescence microscopy
- Single-molecule
ASJC Scopus subject areas
- General